1.4 Attributes

A gEDA user is able to annotate schematic elements with additional
data, such as footprints for components or net names for nets. This
is carried out using attributes.

An attribute is text object which contains a text string in the
form ‘name=value’. Currently, the restrictions on
attribute format that are enforced by the API are:

Attribute names:

must contain at least one character;

must not contain a ‘=’ character (Unicode U+003D);

must not end with a space (‘’, Unicode U+0020).

Attribute values:

must contain at least one character;

must not begin with a space (‘’, Unicode U+0020).

Note: Due to assumptions made by some gEDA tools, it is
strongly recommended that you use attribute names which
contain only lower-case Latin characters, decimal digits, full stops
‘.’ (U+002E), and hyphens ‘-’ (U+002D).

There are two types of attribute:

Attached attributes are attribute text objects that are
linked to another object. To attach an attribute to another
schematic element, both objects must be part of the same
component or part of the same object. For example, a
‘netname=name’ attribute attached to a net object
can be used to give that net a specific name in netlist output, such
as ‘VCC’ or ‘GND’.

Floating attributes are attribute text objects that are
not linked to another object. These attributes affect the
schematic or symbol that they're part of as a whole. For example, a
floating ‘documentation=url’ attribute in a symbol tells
gschem's Help → Component Documentation command how to find
the component's data sheet.